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Simulation of electromagnetic radiation and scattering using a finite difference-time domain technique

computer applications in engineering Education 1992年第1期1卷 45-45页

作者： Li, K. Tassoudji, M.A. Shin, R.T. Kong, J.A. Department of Electrical Engineering and Computer Science and Research Laboratory of Electronics Massachusetts Institute of Technology Cambridge Massachusetts 02139 Kevin Li:received his BS and SM degrees (1990) in Electrical Engineering and EE (Electrical Engineer's) degree (1991) from the Massachusetts Institute of Technology where he is currently pursuing his PhD in Electrical Engineering. Since 1990 he has been the recipient of a United States Air Force Laboratory Graduate Fellowship. His main research interests include electromagnetic scattering radar cross section prediction and numerical techniques. Mr. Li is a member of Tau Beta Pi and a student member of IEEE. M. Ali Tassoudji:received his BS (1987) and MS (1989) degrees in Electrical Engineering from the University of Michigan Ann Arbor. Since 1989 he has been a research assistant at the Massachusetts Institute of Technology where he is currently working towards his PhD in Electrical Engineering. His research interests include electromagnetic scattering and propagation modeling of microwave circuits and numerical techniques. Mr. Tassoudji is a member of IEEE and Eta Kappa Nu. Robert T. Shin:received his SB (1977) SM (1980) and PhD (1984) in Electrical Engineering from the Massachusetts Institute of Technology. Since 1984 he has been a member of the Air Defense Techniques Group at MIT Lincoln Laboratory as a Research Staff member and as a Senior Staff member from 1989. His research interests are in the areas of electromagnetic wave scattering and propagation theoretical model development and data interpretation for microwave remote sensing. He is the coauthor ofTheory of Microwave Remote Sensing(Wiley 1985). Dr. Shin is a member of The Electromagnetics Academy IEEE American Geophysical Union Tau Beta Pi Eta Kappa Nu and Commission F of the International Union of Radio Science. Since 1987 he has served on the Editorial Board of theJournal of Electromagnetic Waves and Applications(JEWA). Jin Au Kong:is Professor of Electrical Enginee

The finite difference-time domain (FD-TD) technique is applied to the solution of Maxwell's equations. A computer program, which can be used to simulate and study numerous electromagnetic phenomena, is developed and implemented on an IBM 386 compatible personal computer. The FD-TD technique is a useful tool for students in electromagnetics. The technique is flexible and can be applied to many basic EM scattering and radiation problems. Because field solutions are found as a function of time, visualization of the propagation of the EM fields is possible. The FD-TD technique is implemented for a two-dimensional rectangular grid in conjunction with a second-order absorbing boundary condition. Both E- and H-field polarizations are analyzed. Finite objects consisting of dielectric, magnetic and conducting materials, and perfectly conducting infinite ground planes are modeled. Plane wave and line current sources are implemented. In addition to the capability of animating the propagation of the EM fields, radiation and scattering patterns can be generated.

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NONLINEAR EVOLUTION OF A 2ND-MODE WAVE IN SUPERSONIC BOUNDARY-LAYERS

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APPLIED NUMERICAL MATHEMATICS 1991年第1期7卷 73-91页

作者： ERLEBACHER, G HUSSAINI, MY NASA Langley Research Center Hampton VA 23665 USA Institute for Computer Applications in Science and Engineering NASA Langley Research Center Hampton VA 23665 USA

The nonlinear time evolution of a second-mode instability in a Mach 4.5 wall-bounded flow is computed by solving the full compressible, time-dependent Navier-Stokes equations. High accuracy is achieved by using a Fourier-Chebyshev collocation algorithm. Primarily inviscid in nature, second modes are characterized by high frequency and high growth rates compared to first modes. Time evolution of growth rate as a function of distance from the plate suggests this problem is amenable to the Stuart-Watson perturbation theory as generalized by Herbert.

关键词： Aerodynamics

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TURBULENT-FLOW CALCULATIONS USING UNSTRUCTURED AND ADAPTIVE MESHES

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INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS 1991年第9期13卷 1131-1152页

作者： MAVRIPLIS, DJ Institute for Computer Applications in Science and Engineering ICASE Mail Stop 132C NASA Langley Research Center Hampton VA 23665 U.S.A.

A method of efficiently computing turbulent compressible flow over complex two-dimensional configurations is presented. The method makes use of fully unstructured meshes throughout the entire flow field, thus enabling the treatment of arbitrarily complex geometries and the use of adaptive meshing techniques throughout both viscous and inviscid regions of the flow field. Mesh generation is based on a locally mapped Delaunay technique in order to generate unstructured meshes with highly stretched elements in the viscous regions. The flow equations are discretized using a finite element Navier-Stokes solver, and rapid convergence to steady state is achieved using an unstructured multigrid algorithm, Turbulence modelling is performed using an inexpensive algebraic model, implemented for use on unstructured and adaptive meshes. Compressible turbulent flow solutions about multiple-element aerofoil geometries are computed and compared with experimental data.

关键词： TURBULENT NAVIER-STOKES UNSTRUCTURED ADAPTIVE

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A NUMERICAL-SIMULATION OF THE APPEARANCE OF CHAOS IN FINITE-LENGTH TAYLOR-COUETTE FLOW

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APPLIED NUMERICAL MATHEMATICS 1991年第1期7卷 41-71页

作者： STREETT, CL HUSSAINI, MY NASA Langley Research Center Hampton VA 23665 USA Institute for Computer Applications in Science and Engineering NASA Langley Research Center Hampton VA 23665 USA

Taylor-Couette flow, the shear-driven flow between concentric cylinders, exhibits a wide variety of instabilities and modal changes, especially for the case of finite length to gap ratio. The numerical simulations presented here capture many of the experimentally observed features, including the moderately high Reynolds number regime in which temporally aperiodic behavior is seen. The exponential decay of the temporal frequency spectrum of these modes in the simulations indicate such flows possess a low-order chaotic character. In this paper, the spectral collocation methods used in this study are described, select axisymmetric simulations are reviewed, and initial results from three-dimensional unsteady simulations are presented.

关键词： Flow of Fluids

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Direct simulation of compressible turbulence in a shear flow

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Theoretical and Computational Fluid Dynamics 1991年第5-6期2卷 291-305页

作者： Sarkar, S. Erlebacher, G. Hussaini, M.Y. Institute for Computer Applications in Science and Engineering NASA Langley Research Center Hampton VA 23665 United States

The purpose of this study is to investigate compressibility effects on the turbulence in homogeneous shear flow. We find that the growth of the turbulent kinetic energy decreases with increasing Mach number-a phenomenon which is similar to the reduction of turbulent velocity intensities observed in experiments on supersonic free shear layers. An examination of the turbulent energy budget shows that both the compressible dissipation and the pressure-dilatation contribute to the decrease in the growth of kinetic energy. The pressure-dilatation is predominantly negative in homogeneous shear flow, in contrast to its predominantly positive behavior in isotropic turbulence. The different signs of the pressure-dilatation are explained by theoretical consideration of the equations for the pressure variance and density variance. We previously obtained the following results for isotropic turbulence: first, the normalized compressible dissipation is of O(M_t²), and, second, there is approximate equipartition between the kinetic and potential energies associated with the fluctuating compressible mode. Both these results have now been substantiated in the case of homogeneous shear. The dilatation field is significantly more skewed and intermittent than the vorticity field. Strong compressions seem to be more likely than strong expansions. © 1991 Springer-Verlag.

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Three dimensional unstructured multigrid for the Euler equations

Three dimensional unstructured multigrid for the Euler equat...

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10th Computational Fluid Dynamics Conference, 1991

作者： Mavriplis, D.J. Institute for Computer Applications in Science and Engineering NASA Langley Research Center HamptonVA United States

The three-dimensional Euler equations are solved on unstructured tetrahedral meshes using a multigrid strategy. The driving algorithm consists of an explicit vertex-based finite-element scheme, which employs an edge-based data-structure to assemble the residuals. The multigrid approach employs a sequence of independently generated coarse and fine meshes to accelerate the convergence to steady-state of the fine grid solution. Variables, residuals and corrections are passed back and forth between the various grids of the sequence using linear interpolation. The addresses and weights for interpolation are determined in a preprocessing stage using an efficient graph traversal algorithm. The preprocessing operation is shown to require a negligible fraction of the CPU time required by the overall solution procedure, while gains in overall solution efficiencies greater than an order of magnitude are demonstrated on meshes containing up to 350,000 vertices. Solutions using globally regenerated fine meshes as well as adaptively refined meshes are given. © 1991 by the American institute of Aeronautics, and Astronautics, Inc. All rights reserved.

关键词： Euler equations

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Simulated annealing-based channel routing on hypercube computers 4

Simulated annealing-based channel routing on hypercube compu...

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4th CSI/IEEE International Symposium on VLSI Design, VLSI 1991

作者： Mall, R. Patnaik, L.M. Raman, S. Dept. of Computer Science and Automation Microprocessor Applications Laboratory Supercomputer Education and Research Centre Indian Institute of Science Bangalore560012 India Dept. of Electrical and Computer Engineering Coordinated Science Laboratory University of Illinois Urbana-ChampaignIL61801 United States

ISBN: (纸本)0818621257

Many times, routing of signal nets in the layout design of VLSI circuits turns out to be a bottleneck in designing complex chips, due to the inherent compute-intensive nature of this task. Parallel processing of the routing problem holds promise for mitigating this situation. The authors present a parallel channel routing algorithm that is targetted to run on loosely coupled computers like hypercubes. The proposed parallel algorithm employs simulated annealing technique for achieving near-optimum solutions. For efficient execution, attempts have been made to reduce the communication overheads by restricting broadcast of updates only to cases of interprocessor net transfers. Performance evaluation studies on the algorithm show promising results. © 1991 IEEE.

关键词： Simulated annealing

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Simulated annealing-based channel routing on hypercube computers

Simulated annealing-based channel routing on hypercube compu...

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CSI/IEEE International Symposium on VLSI Design

作者： R. Mall L.M. Patnaik S. Raman Department of Computer Science and Automation Indian Institute of Science Bangalore India Department of Computer Science and Automation Mircroprocessor Applications Laboratory Supercomputer Education and Research Centre Indian Institute of Science Bangalore India Department of Electrical and Computer Engineering and Coordinated Science Laboratory University of Illinois Urbana-Champaign IL USA

关键词： Computational modeling computer simulation Simulated annealing Routing Hypercubes Signal design Circuit simulation Very large scale integration Parallel processing Coupling circuits

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A parallel algorithm for logic simulation on transputer networks

A parallel algorithm for logic simulation on transputer netw...

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Great Lakes Symposium on VLSI

作者： S. Srinivas A. Basu A. Paulraj L.M. Patnaik Department of Electrical and Computer Engineering Concordia University Montreal QUE Canada Centre for Development of Advanced Computing Bangalore India Microprocessor Applications Laboratory Supercomputing Education and Research Center Department of Computer Science and Automation Indian Institute of Science Bangalore India

The authors present a parallel algorithm for logic simulation of VLSI circuits. It is implemented on a network of transputers connected in a ring topology. The approach is based on partitioning a functionality matrix representation of the circuit among the transputers and adopting a data flow technique for the solution. A significant aspect of the algorithm is that it overlaps computation with communication, thereby reducing the communication overhead. It also attempts even distribution of load in order to reduce processor idle time. The algorithm possesses the advantages of ease of implementation and ease of extension to incorporate additional parameters for simulation. Performance results of the algorithm are given.< >

关键词： Parallel algorithms Circuit simulation Computational modeling Concurrent computing Application software Logic circuits Very large scale integration Algorithm design and analysis Logic design Design automation

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FULL-WAVE SOLUTION OF DIELECTRIC LOADED WAVE-GUIDES AND SHIELDED MICROSTRIPS UTILIZING FINITE-DIFFERENCE AND THE CONJUGATE-GRADIENT METHOD

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INTERNATIONAL JOURNAL OF MICROWAVE AND MILLIMETER-WAVE computer-AIDED engineering 1991年第4期1卷 346-357页

作者： NARAYANAN, V MANELA, M LADE, RK SARKAR, TK Department of Electrical and Computer Engineering Syracuse University Syracuse New York 13244-1240 Viswanathan Narayanan was born in Bangalore India on December 14 1965. He received the BE degree in Electronics and Communications from B.M.S. College of Engineering Bangalore in 1988. He joined the Department of Electrical Engineering at Syracuse University for his graduate studies in 1989 where he is currently a research assistant. His research interests are in microwave measurements numerical electromagnetics and signal processing. Biographies and photos are not available for M. Manela and R. K. Lade. Tapan K. Sarkar (Sf69-M'76-SM'X1) was born in Calcutta. India on August 2 1948. He received the BTech degree from the Indian Institute of Technology Kharagpur India in 1969 the MScE degree from the University of New Brunswick Fredericton Canada in 1971. and the MS and PhD degrees from Syracuse University. Syracuse NY in 1975. From 1975-1976 he was with the TACO Division of the General Instruments Corporation. He was with the Rochester Institute of Technology (Rochester NY) from 1976-1985. He was a Research Fellow at the Gordon Mckay Laboratory Harvard University Cambridge MA from 1977 to 1978. He is now a Professor in the Department of Electrical and Computer Engineering Syracuse University. His current research interests deal with numerical solutions of operator equations arising in electromagnetics and signal processing with application to system design. He obtained one of the “ best solution” awards in May 1977 at the Rome Air Development Center (RADC) Spectral Estimation Workshop. He has authored or coauthored more than 154 journal articles and conference papers and has written chapters in eight books. Dr. Sarkar is a registered professional engineer in the state of New York. He received the Best Paper Award of the IEEE Transactions on Electromagnetic Compatibility in 1979. He was an Associate Editor for feature articles of the lEEE Antennas arid Propagation Sociefy Newsletter and was

Dynamic analysis of waveguide structures containing dielectric and metal strips is presented. The analysis utilizes a finite difference frequency domain procedure to reduce the problem to a symmetric matrix eigenvalue problem. Since the matrix is also sparse, the eigenvalue problem can be solved quickly and efficiently using the conjugate gradient method resulting in considerable savings in computer storage and time. Comparison is made with the analytical solution for the loaded dielectric waveguide case. For the microstrip case, we get both waveguide modes and quasi-TEM modes. The quasi-TEM modes in the limit of zero frequency are checked with the static analysis which also uses finite difference. Some of the quasi-TEM modes are spurious. This article describes their origin and discusses how to eliminate them. Numerical results are presented to illustrate the principles.

关键词： Waveguides

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